I always believed that there were none, but on a rewatch of QI, I learned there are actually two:
- Hurple / hirple: To limp (verb) or a limping gait (noun)
- Curple: A strap under the girth of a horse’s saddle to stop the saddle from kicking forward.
YouTube: QI | What Rhymes With Purple?
If you’re interested in words, Something Rhymes with Purple is a podcast with Susie Dent and Gyles Brandreth.
Whenever Gyles is on Qi, about half the episode is him going off on an anecdote.
Edit: Fixed spelling